Approximately what percent of milk is water?

• A. 70%
• B. 87.7% water
• C. 50%
• D. 60%

Answer: (B)

Milk is mostly water, with the rest made up of fats, lactose, proteins, and minerals dissolved or dispersed in that water. In typical whole milk, the water portion is about 87.7% by weight, leaving roughly 12% for solids like fat, lactose, proteins, and minerals. That large water share explains why milk behaves like a mostly watery liquid even though it contains several percent of solids. The other options imply much more solid material than milk actually has, which doesn’t fit the real composition. Skim milk can have a bit more water, but the commonly cited figure for whole milk is about 87.7%, making it the best match.